e a pillar of
t very little
7 since Hum-
ains, and to
ted for our
time, geology
\d not been
5 now exists,
. with absurd
ANDES.
uld, in fact,
inate that as
reat mass of
ch form its
which form
ost as exten-
is now, and
1t’s observa-
lay. Not so
r formations.
wn, and the
hronological
descriptions
s to modern
leaned from
rs who have
to them we
wble to give
vt an epoch
- Mountains
ally a con-
, to a very
rocks. It
n not as an
intercalated
azoic series.
he trappean
everywhere
ies of trap
ry). These
wr at a dis-
ery striking
are a nums-
with more
ntains spe-
Corcobado,
1, Cotopaxi,
ass, Fifty-
1S existing
untains of
nuously of
>garded as
me burning
re is a rela-
its activity
, Stromboli
bivity since
light-house
ea ; while
6,679 feet)
red years.
uently not
tive state.
, and 7 of
e numbers
y in all 36
me uncer-
wracteristic
rantic alti-
s of lava.
the Quito
. however,
nse super-
exhibited
in a terrific manner when an eruption does take
place. Cotopaxi, for instance, the most regular and
beautiful outlet of this the grandest of nature’s
laboratories, has been known to shoot its fiery tor-
rents 3000 feet above its snow-bound crater, while
its voice is said to have been heard at a distance
of 550 miles. On one occasion a piece of rock,
measuring 300 -cubic feet, was thrown from its
crater to a distance of more than eight miles.
Harthquakes are intimately connected with these
volcanic phenomena. No portion of the globe is sub-
ject to such frequent and destructive earthquakes as
the countries embosomed within the range of the
A. and those lying between them and the Pacific.
The cities and towns of Bogota, Quito, Riobamba,
Callao, Copiapo, Valparaiso, and Concepcion, have
all at different times been more or less devastated
by their agency. During the present year (1859), an
earthquake buried many of the inhabitants of Quito
under the ruins of its churches and public edifices ;
scarcely a single building of any size escaped un-
injured.
It is to the same subterranean agency that
upheaved and still convulses the A. that we are
to ascribe those fearful ravines which are almost
peculiar to the chain. An apt instance has already
been cited in the case of the deep and dismal crevice
which has been spanned by the natural bridges of
Icononzo. A still better specimen is the valley or
den of Chota, which, with a width at top of only
2600 feet, is 4875 feet in perpendicular height. This
den might overlap the loftiest hill in Scotland, with
St Peter’s at Rome on its summit.
The flanks of the mountains are clothed with
crystalline stratified rocks, consisting of innumer-
able varieties of granites, gneiss, schists, horn-
blende, chloritic slates, porphyries, &c. These
have been greatly disrupted by the underlying
igneous rocks, and now occupy a vertical or nearly
vertical position. They often run up into bold and
rugged peaks on the summits. They alternate with
each other in great meridional bands, but without
any apparent order in the succession, except that
the varieties of schist depend on the crystalline
parent rock below ; otherwise, no regular sequence
can be observed ; for miles, only granite and gneiss
are found, then schist, quartz, gneiss, &c., inter-
changing. The variety and quantity of the mineral
wealth of these rocks is remarkable; with the
exception of lead, most of the metals are obtained
in large quantities—see below. The topaz, ame-
thyst, and other gems are abundant.
Lying unconformable with these almost vertical
metamorphic rocks, there occur in the valleys and
table-lands, and creeping up the base of the moun-
tains, a variety of fossiliferous beds, which require
further examination before they can be clearly
understood. A better estimate of the nature of
these deposits will be arrived at by describing one
of the localities where they occur. Take the large
plateau on which Bogota is built, which is 8958 feet
above the sea. The deposits filling up this plain
have been formed subsequent to the present con-
formation of the district, though not necessarily at
the present altitude: the whole range may have
been since elevated. The almost horizontal rocks,
from their organic contents, consisting of Ammonites,
Hamites, &c., have been referred by Edward Forbes
to the cretaceous era. The basin consists of many
beds of sandstones, limestones, shale, coal, gypsum,
and salt. The salt occurs in large quantities, one
bed being no less than 100 feet in thickness, and
the coal in sufficient abundance to be wrought. All
these rocks have been more or less affected by their
proximity to the underlying metamorphic rocks.
The m;)éecular action going on below has in many
places been continued in them, and has induced a
cleavage at right angles to their planes of stra-
tification. The other patches—some of great
extent, as the plateau of the Titicaca—cannot yet
be referred to any-particular geologic epoch. Coal
has been found near Huanco, in Peru, at the height
of 17,000 feet; fossiliferous limestones and sand-
stones have been noticed in Peru at Micuipampa.
and Huancavelica.
Metals.—The aboriginal term A. is said to have
been derived from the Peruvian ante, which signifies
metal in general, or rather, perhaps, copper in par-
ticular. Within the limits of the empire of the
Incas, mining-tools, evidently not European, have
been dug up in various places; and in one district
the ancient Peruvians have left behind them traces
of their mining operations at a height of 17,000 feet.
Moreover, the term, whatever may have been its
meaning, appears to have been, at all events, of
Peruvian origin, for it does not seem to have been
applied to the -great chain of mountains by the
aborigines of New Granada.
The A. are understood to yield every metal
used in the arts but lead, and, according to one
recent statement, they yield lead also.
Gold is found in Chili, Peru, and New Granada.
In Chili, however, it is so little productive, that
proverbially a gold-mine is inferior to a silver one,
and that, again, to a copper one. In Peru, gold is
most abundant between the 9th and 7th parallels ;
though further south, to the east of Lima, the
mines of Carabayo have been recently wrought to
great advantage; and further south still, to the east
of Titicaca, very rich washings are situated on the
river Tipuani. In New Granada, gold-mines are
generally so inaccessible as not to bear the expense
of working them. The washings, again, though per-
haps remotely the product of the A., are confined
chiefly to the alluvial soils that lie between the
chain and either sea.
Silver also is found in Chili, Peru, and New
Granada. In Chili, the most valuable, almost the
only very valuable, mines are wrought on the east
face of the A., not far from the city of Mendoza,
already mentioned in connection with the breadth of
the chain. In Peru, the most productive mines are
those of Pasco and Potosi. In those of Pasco, which
have now been open for more than two and a
quarter centuries without even approaching to
exhaustion, the ore is a mixture of silver and oxide
of iron. In the mines, again, of Potosi, whose very
name has become a proverb, there are said to be no
fewer than 5000 excavations, while, to all appear-
ance, only the upper crust of the inexhaustible
deposits has been penetrated. In New Granada, it
is with silver as it has been shewn to be with gold,
the mines of the former metal, as well as of the
latter, being so inaccessible as not to bear. the
expense of working them.
Mercury or quicksilver is found in Quito, near the
village of Azogué, which lies to the north-west of
Cuenc¢a—taking its name, as is said, from this metal ;
and it is found likewise in Peru, not far from
Guancavelica, a town situated, as already stated, to
the north of the group of Cuzco. The mercury
exists chiefly in combination with sulphur, forming
what is called cinnabar.
Plaiinum appears to exist only in New Granada ;
but like the gold-washings of that country, it is
found rather in the alluvial soils, that have been
flooded down from the chain, than in the chain
itself.
Copper is found chiefly in Chili, but also in Peru.
In the latter country, it is of little account in com-
parison with silver; but, in the former, it may be
styled the staple metal, or even the staple prod;;(l:’mon.
